神经信号经皮传输的电路设计与仿真实验

本研究旨在实现利用神经动作电信号控制多自由度假肢。针对植入的神经信号电极,研究了神经信号的放大。为了使植入电极测得的神经信号能无线地传至体外,作者借助E类功率放大器的输出功率受负载电阻影响的特点,通过时分复用技术实现了多路神经信号的经皮传输与识别。文中叙述的植入体内的放大电路、经皮发射电路均是通过体外E类功率放大器发射的射频磁场经感应线圈而获得工作电源。最后用本研究研制的电路模拟神经信号控制多自由度假肢,验证了神经信号的放大、经皮传输、识别控制的过程。     

一种动物实验监控系统的设计

本文主要设计动物生命体征参数(体温、呼吸率和脉搏率)的监控系统。硬件电路采用MSP430F5438芯片作为微控制器,体温、呼吸和脉搏生理参数的信号采集使用了相应的信号调理电路和处理电路,主要由电信号转换电路、放大滤波电路、AD转换电路、脉冲转换电路、LCD显示电路、加热垫和蜂鸣器驱动电路等组成。     

压力传感器信号调理电路设计

详细介绍了循环式氦氧混合气辅助呼吸装置压力传感器信号调理电路传感器接入、电流源、差分放大器、输出放大器、非线性调整环、频率响应等功能模块的设计,明确给出了信号调理电路差分放大器及零点调整电路中电阻的计算方法.测试结果表明:该压力传感器信号调理电路在实现大电压信号满量程输出、输出电压与输入压力保持线性关系、零点电压提升等功能方面取得了很好的效果.     

基于薄膜压力传感器的脉搏信号测试系统

人体脉搏信号携带有丰富的与健康相关的生理信息.为了方便脉搏信号的采集和研究,本文设计出一种采用轻触式薄膜按键面板工艺的自制脉搏压力传感器,并使用了常见的555和V-f转换器件将传感器压力信号转换为电信号,再通过后续设计的滤波、陷波放大电路以及电路的干扰抑制处理,系统就可以获取高质量的脉搏波信号.传感器的性能测试以及示波器的应用结果表明,基于薄膜压力传感器的脉搏信号测试系统工作性能稳定,并通过示波器的串口通信扩展模块或者LABVIEW采集卡可以在计算机上显示出采集的脉搏信号,此测试系统可用于脉象信息的采集与研究.     

DWF-2微电极放大器前放电路的设计和噪声指标的探讨

一、微电极实验系统生物电信号如:心电、脑电、肌电神经电位等目前已成为临床诊断和生理、药理研究的重要指标和依据.从微观来看,所有这些生物电信号都来源于细胞电位的总和.对细胞兴奋性的深入研究促进了细胞生理学、微量药理学以及相应的微电极实验技术的迅速发展,使某些领域为之面貌一新,许多难解之谜得到了较好的解释.     

心电、呼吸信号采集分析系统的研制

设计一种用于移动监护系统的生理信息采集及预处理装置.该装置以ARM为核心,包括低功耗的双路心电信号放大、滤波、抗基线漂移电路.实现了心电信号的采集、预处理、简单分析及从心电信号中提取呼吸信号等功能.     

肌电信号的预处理

通过观察肌电信号(EMG)可以判断肌肉功能是否正常,这对利用A型肉毒毒素治疗肌肉痉挛性疾病十分有意义。EMG属于生物电范畴,信号微弱,并且易受干扰,针对EMG的特点设计信号调理电路。该电路采用两级隔离放大并经过滤波处理来提取肌电信号。对信号处理电路的特性分析表明,文中所设计的电路可以有效提取10～500Hz的肌电信号,并有效抑制工频干扰,因此该电路将在实际应用中取得较理想结果。     

采集表面肌电信号应用于动作识别的可行性

背景：文献表明上肢前臂运动时所产生的表面肌电信号具有非线性特征,而肢体运动时肌电信号又呈现出非平稳特性。 目的：设计一种简单的拾取电路采集表面肌电信号,拟应用于动作肌电信号的特征识别。 方法：根据表面肌电信号的特点,设计高共模抑制比的前端放大电路,抑制共模干扰;采用低通滤波电路,有源双T带阻滤波器对信号进行去噪处理;对采集得到的信号进行小波包变换,得到信号的特征量。 结果与结论：所设计的表面肌电信号检测电路具有较高共模抑制比,并能有效地滤除50 Hz工频信号,可以满足肌电信号采集电路的基本要求。肌电信号的处理结果表明采用子频段能量值的方法可以区分手部4种不同动作。     

自适应干扰对消技术提取胎儿心电的可视化仿真实现

目的:用可视化编程技术实现胎儿心电信号提取和分析.方法:获取受试者仰卧位的腹部平行放置的两对电极的二道心电信号;在Windows系统下,用Delphi嵌入汇编技术实现对模/数采样卡的低层I/O操作;用自适应干扰对消技术提取胎儿心电信号.结果和结论:计算机仿真结果表明,该方法能获取较清晰的胎儿心电信号.讨论:①基于Windows开发的系统具有较好的交互性和移植性,②获得胎儿心电后可用我们已开发的成熟技术实现对胎儿心动周期信号的混沌特征分析,以估计胎儿自主神经系统功能.     

50Hz滤波电路对心肌细胞自发动作电位波形分析的影响

目的：研究微电极放大器中的50Hz滤波电路对心肌细胞自发动作电位波形及各项参数的影响。方法：将心肌细胞自发动作电位经玻璃微电极、微电极放大器、微分器、A／D转换器输入微型计算机。在应用和不应用微电极放大器中50Hz滤波功能两种情况下,对心肌细胞自发动作电位波形进行比较分析。结果：在使用微电极放大器中50Hz滤波功能情况下,动作电位波形在0相严重失真,时程延长,除极化最大速度减小;复极化50％、90％的时间延长;其它参数无显著变化。结论：心肌细胞动作电位波形中含有50Hz信号成分,在研究心肌细胞动作电位信号时,不能使用50Hz滤波器。如果使用50Hz滤波器,会造成动作电位波形严重失真,影响实验结果。     

The foreign body response to the Utah Slant Electrode Array in the cat sciatic nerve

As the field of neuroprosthetic research continues to grow, studies describing the foreign body reaction surrounding chronic indwelling electrodes or microelectrode arrays will be critical for assessing biocompatibility. Of particular importance is the reaction surrounding penetrating microelectrodes that are used to stimulate and record from peripheral nerves used for prosthetic control, where such studies on axially penetrating electrodes are limited. Using the Utah Slant Electrode Array and a variety of histological methods, we investigated the foreign body response to the implanted array and its surrounding silicone cuff over long indwelling periods in the cat sciatic nerve. We observed that implanted nerves were associated with increased numbers of activated macrophages at the implant site, as well as distal to the implant, at all time points examined, with the longest observation being 350 days after implantation. We found that implanted cat sciatic nerves undergo a compensatory regenerative response after the initial injury that is accompanied by shifts in nerve fiber composition toward nerve fibers of smaller diameter and evidence of axons growing around microelectrode shafts. Nerve fibers located in fascicles that were not penetrated by the array or were located more than a few hundred microns from the implant appeared normal when examined over the course of a year-long indwelling period.     

对大鼠受损视网膜节细胞形态影响因素的研究

切断大鼠视神经后,将坐骨神经段和视神经段以不同方式植入眼玻璃体内,4周后观察视网膜节细胞的形态,并用计算机图像分析仪(IBAS-2000)测量胞体截面积。结果表明,不同种类的移植物对受损视网膜节细胞形态影响是不同的。在坐骨神经段植入的胞体截面积均值和特巨细胞构成比均增大。如预先把坐骨神经挤压1周后再植入,或者一眼同时植入坐骨神经段和视神经段时,则增大更明显。     

微囊牛嗜铬细胞移植镇痛作用的实验研究

目的 观察微囊牛嗜铬细胞（BCC）的镇痛作用；方法 应用胶原酶消化法分离、提取牛嗜铬细胞，进行APA微囊化；制作大鼠坐骨神经结扎和福尔马林实验疼痛动物模型，模型大鼠各分为4组（微囊BCC组、裸细胞组、空囊组和生理盐水组），分别在蛛网膜下腔植入微囊化BCC、未包囊BCC、空囊和生理盐水，观察坐骨神经结扎疼痛模型动物冷、热刺激后的行为学变化及福尔马林疼痛模型动物福尔马林刺激后的行为学变化；结果 坐骨神经结扎实验动物冷、热刺激后，徵中BCC组冷刺激收缩时间、次数和热刺激潜伏期差异分数明显下降，裸细胞组下降只维持了2周，而空囊组和生理盐水组无变化；福尔马林实验动物刺激后，微囊BCC组收缩次数下降了13周以上，裸细胞组下降只维持了2周，而空囊组和生理盐水组无变化；结论 微囊牛嗜铬细胞对异种动物疼痛具有镇痛作用。     

Neurotropism in nerve regeneration: an immunohistochemical study

A rectangular pseudomesothelial-lined chamber was used to elucidate the hypothesis that in adult rats neurotrophic factors are formed after nerve injury and may influence regeneration of peripheral nerves. The proximal end of a cut sciatic nerve was inserted into one corner of the chamber. In one group of animals the distal end of the cut sciatic nerve was implanted in the diagonally opposite corner of the chamber. In another group we just introduced the proximal end of the sciatic nerve; no distal implant was used. The organization, length and direction of the nerve fibres, regenerating from the proximal end of the sciatic nerve, was visualized immunohistochemically with the aid of antibodies against neurofilaments at 2, 3 and 4 weeks after surgery. When a distal sciatic nerve segment was used, nerve fibres regenerating from the proximal cut end of the sciatic nerve showed an organized growth across the chamber, formed bundles and grew into the diagonally implanted nerve piece. If there was no distal implant, the growth of the randomly directed nerve fibres ceased after about two weeks, resulting in formation of a neuroma-like structure. Increased immunoreactivity of the trophic peptide insulin-like growth factor I (IGF-I, somatomedin C) was demonstrated in the regenerating nerve, most evidently in reactive Schwann cells. It is concluded that a positive neurotropic effect is exerted on growing nerve fibres by injured, reactive peripheral nerve tissue. There could tentatively be a relation between nerve regeneration and local formation of trophic factors.     

Flexible printed-circuit probe for electrophysiology

Photofabrication techniques have been used to produce a nickel-iron microelectrode array on Kapton film specifically designed for biological implantation. The probe is 2·5 mm×2 mm and carries four tissue terminals, each 2 μm in width. Both spontaneous and evoked potentials have been recorded from frog sciatic nerve. Developmental possibilities for the probe are fully discussed.     

Noradrenergic mechanism involved in the nociceptive modulation of nociceptive-related neurons in the caudate putamen

Norepinephrine (NE) participates in pain modulation of the central nervous system. The caudate putamen (CPu) is one region of the basal ganglia that has been demonstrated to be involved in nociceptive perception. Our previous work has shown that microinjection of different doses of norepinephrine into the CPu produces opposing effects in the tail-flick latency (TFL) of rats. However, the mechanism of action of NE on the pain-related neurons in the CPu remains unclear. The present study examined the effects of NE and the alpha-adrenoceptor antagonist phentolamine on the pain-evoked response of pain-excitation neurons (PENs) and pain-inhibition neurons (PINs) in the CPu of rats. Trains of electric impulses were used for noxious stimulation, and were applied to the sciatic nerve. The electrical activities of pain-related neurons in the CPu were recorded by a glass microelectrode. The results revealed that intra-CPu microinjection of NE (8 μg/2 μl) increased evoked firing frequency of PEN and shortened the firing latency, but decreased the evoked firing frequency of PIN and prolonged the inhibitory duration (ID). Intra-CPu administration of phentolamine (4 μg/2 μl) showed the opposite effects. The above results suggest that NE in the CPu modulates nociception by affecting the baseline firing rates of PENs and PINs.     

微囊化兔坐骨神经组织细胞移植对脊髓损伤后大鼠GDNF表达的影响

目的探讨微囊化兔坐骨神经组织细胞移植对脊髓半横断损伤后大鼠胶质细胞源性神经营养因子（GDNF）的表达影响。方法成年SD大鼠80只随机分为4组,微囊组（n=25）、细胞组（n=25）、单损组（n=25）、正常组（n=5）。术前制备兔坐骨神经细胞混悬液以及将其微囊化,微囊组、细胞组和单损组大鼠在脊髓半横断伤后,立即在损伤处分别植入10μl微囊化坐骨神经组织细胞1、0μl坐骨神经组织细胞以及10μl生理盐水。于术后2 d7、d1、4 d、21 d2、8 d（每个时相取5只大鼠）取出损伤部位脊髓组织,正常组（每个时相取1只大鼠）则取相应节段脊髓。组织石蜡包埋后切片,行免疫组织化学染色观察GDNF的表达变化。结果 GDNF阳性染色主要见于神经元细胞及胶质细胞的胞浆内。大鼠脊髓损伤后上述细胞2 d后表达开始上升2,1 d达到最高。微囊组与单损组、细胞组比较差异有显著性（P〈0.05）。结论微囊化兔坐骨神经组织细胞移植于大鼠损伤脊髓后,可以抑制炎症反应,促进GDNF的表达,有利于大鼠运动功能恢复。     

p27kip1和Skp2在损伤后大鼠坐骨神经中的表达变化

为了探讨损伤后周围神经p27kip1和S期激酶相关蛋白2(Skp2)的定位表达和变化,本实验将成年SD大鼠随机分为正常对照组、夹伤组和切断组,运用Western blot结合免疫组织化学及免疫荧光双标,在大鼠坐骨神经损伤时,对p27kip1和Skp2表达的影响进行了研究。结果表明:(1)坐骨神经夹伤后,p27kip1蛋白表达先逐渐下降,后又逐渐上升;坐骨神经切断后,远侧段p27kip1蛋白表达持续下降,而近侧段p27kip1蛋白表达在切断后6h明显下降,后又逐渐升高至正常水平,而Skp2表达变化与之相反;(2)免疫组织化学染色结果显示,坐骨神经切断后1w,远侧段从断端到末端,p27kip1阳性信号逐渐增加,而Skp2阳性信号逐渐减弱;(3)免疫荧光双标显示,正常和损伤坐骨神经的雪旺氏细胞中都有p27kip1和Skp2表达。以上结果提示:周围神经损伤后影响雪旺氏细胞中p27kip1和Skp2的表达变化,为进一步研究它们在周围神经损伤和修复中的作用机制奠定基础。     

The brief and the prolonged facilitatory effects of unmyelinated afferent input on the rat spinal cord are independently influenced by peripheral nerve section

Single C-fibre strength stimuli applied to the sciatic nerve in the decerebrate spinal rat evoke three separate bursts of activity in posterior biceps/semitendinosus flexor alpha motorneurones which are associated with the arrival in the spinal cord of volleys in the A-beta, A-delta and C-afferent fibres. Repetitive stimulation of the sciatic nerve at 1 Hz for 20 s generates a progressive wind-up of response and an after-discharge lasting up to 10 s. Twelve to fourteen days after section of the sciatic nerve, stimuli applied central to the section evoke a larger than normal response in the posterior biceps/semitendinosus flexor motorneurones and repetitive stimulation (1 Hz, 20 s) produces an after-discharge which is four times longer than that produced by stimulation of the intact nerve. In addition to the direct excitatory effects of sciatic nerve stimulation on the flexor motorneurones which lasts for seconds, conditioning stimuli to the sciatic nerve at C-fibre strength (1 Hz, 20 s) produce a facilitation of the flexor reflex evoked by a standard pressure stimulus to the ipsilateral and contralateral toes which lasts for 70 min. However, although the direct excitatory effects of stimulating a sectioned sciatic nerve on the posterior biceps/semitendinosus flexor motorneurones are exaggerated, the facilitation of the cutaneous flexion reflex evoked by stimulating sectioned sciatic nerves (1 Hz, 20 s) only lasts for 17 min. These results show that the mechanism which produces the rapid effects of sciatic nerve stimulation on the flexor reflex circuit can be separated from the mechanism which produces the prolonged facilitation.(ABSTRACT TRUNCATED AT 250 WORDS)